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. C. H. NORTON. DOUBLE HEAD GRINDIN G MACHINE. 'APi'ucmou FILED JULY 1. 1911.

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Patented May 27, 1919.

C. H. NORTON.

DOUBLE HEAD GRINDING MACHINE.

APPLICATION FILED JULY 7. l9lZ- Patented May 27, 1919.

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DOUBLE HEAD GRINDING MACHINE.

APPLICATION FILEID JULY 7.19M.

Patented May 27, 1919.

UNITED STATES PATENT oruron CHARLES H, NORTON, OF WORCESTER, MASSACHUSETTS, ASSIGNOR TO NORTON GRINDING COMPANY, OF WORCESTER, MASSACHUSETTS, A. CORPORATION CF MASSACHUSETTS. r

DOUBLE-HEAD GRINDING-MACHINE.

Specification of Letters Patent.

Application filed July 7, 1917. Serial No. 179,255.

To all whom it may concern Be it known that 1, CHARLES H. NORTON, a citizen of the United States of America, residing at Worcester, in the county of VVorcester and State of Massachusetts, have inv ented certain new and useful Impro ements in Double-Head Grinding-Machines, of which the following is a full, clear, and exact specification.

My, invention relates to machinery for cylindricalgrinding and more particularly to a double head machine having driven work-holding spindles.

In certain fields of grinding it has been considered desirable to utilize a double head grinding machine and support the work on rotating spindles driven from both ends instead of from the head stock alone. This type of drive mechanism has, however, been the source of various difliculties in grinding such articles as automobile crankshafts, since the spindles become loose in their bearings and get out of alinement or are improperly rotated, and the crankshaft, which must be securely fastened to the spindles, buckles and twists or is otherwise afi'ected to produce imperfect grinding. The permissible error in grinding operations is very small, it being frequently necessary to measure the work being ground to 0.00025 of an inch; hence a slight change in the location of a work-supporting center, which could be ignored in other arts, ,would produce material and detrimental effects in this art and would render the duplication of fine work exceedingly diilicult. Therefore, in order to avoid serious grinding difiicplties, it is necessary that the work be not only firmly held in axial alinement with supporting centers and rotated evenly and without distortion strains in' true relation to the grinding wheel, but maintained there for a considerable period of time and be capable of being easily and finely adjusted into its correct position for grinding.

It is an object of my invention to overcome these difiiculties heretofore found and to provide such a construction of grinding machine and more particularly the heads and working-holding parts thereof that positively driven or live spindles may be employed as centers to support and rotate the work and extremely fine grinding results may be accomplished and duplicated indefinitely, and so that each piece of work to be ground'may be exactly located relative to the grinding element and may be Patented May 27, 1919. J

accurately centered and thereafter main tained in a correct position for grinding.

A further object is to provide a fine precision means by which the alinement of the spindles may be easily and correctly restored after their utility has become impaired by frictional wear of the relatively rotated parts.

A further object is to provide means for driving the spindles positively and in perfeet synchronism for every position of the work-holding heads and to adjust for wear in the gear connections between the heads, so as to maintain the spindles in properly timed rotative relation for impressing equal torques upon two ends of the work.

.A further object is to provide a double head grinding machine havin duplicate heads and work-holding spin les with a simple, accurate means for determining when the spindles are in axial a'linement and parallel to a fixed guide on the machine.

With theseand other objects in view, as will appear from the disclosure hereinafter made, my invention resides in the combination of parts illustrated in the drawings and described in this specification and covered by the claims annexed hereto.

A preferred form of my invention is shown in the drawings in which Figure 1 is a front elevation of a grinding machine embodying my improvements Fig. 2 is a sectional transverse elevation taken along the line 22 in Fig. 1;

Fig. 3 is a vertical sectional view taken along the line 33 in Fig. 4;

Fig. 4 is a vertical sectional view of one of the spindle heads, taken substantially along the axis of the work-supporting spindle;

Fig. 5 is a vertical sectional view taken along the line 5 5 in Fig. i;

Fig. 6 is a partial sectional View taken along the line 6-43 in Fig. 4; I

Fig. 7 is a perspective view of one of the lower bearing members, and

Fig. 8 is a perspective view of one of the adjusting wedges.

Referring to the drawings, I have there preferred construction, except as specifically and 14 movable longitudinally of the table 12 for positioning the work relative to a rotatively supported grinding element A, diagrammatically indicated in Figs. 1 and 2. A pinion l5 v(Figs. 2 and 3) is formed on a stud 16 mounted in each of the heads 13 and 1'4, said pinion engaging a rack 17 secured to the table 12.- The stud 16 is provided with a squared head 18 to which a handle or wrench may be applied to rotate the stud and pinion, and thus adjust the head longitudinally of the table. A clamping bolt 19 is also provided by which the head may be rigidly secured in adjusted position.

Since the Work heads are similar in construction, but one of them will be described in detail. Rotata-bly mounted in bearings in each of the heads 13 and 14 is a driven spindle 20 carryin a work-holder to support the cranksha t or other object being ground. Each spindle 20 has a gear 21 fastened thereto as by a set-screw at its central portion, this gear being so positioned as to minimize inequalities of frictional wear on different parts of the bearings. The gear 21 engages pinion 22 (Fig. 3) fixed to a shaft 23 having a bearing in the head and extending longitudinally therefrom, as indicated in Fig. 1.

A gear 24 is keyed to the extendad portion of the shaft 23, the shaft being freely slidable through said gear. Longitudinal adjustment of the head is thus permitted, while the gear 24 remains in fixed longitudinal position relative to the tables 10 and 12. The gear 24 is each head meshes with a gear 25 fixed to a driving shaft 26 mounted in hearings in the table 12 and longitudinally movable therewith. The driving shaft 26 is rotated by any suitable driving means (not shown). Provision is thus made for continuously rotating the spindles 20 from the driving shaft 26.

I have provided for the taking up of all lost motion between the pinion 22 and the gear 21 by adjustably mounting a toothed ring 31 upon the side of the gear 21. The ring 31 has a slot and bolt connection with the gear 21 and may be so adjusted that the teeth of the ring will be slightly out of alinement with the teeth of the gear, thus in effect, broadening the teeth to compensate for any wear of the gear or pinion. By this means I insure accurately timed driving of the two spindles, so that they rotate in synchronism, thereby obviating torsion strains on the work. 7

In order to produce the fine, accurate rcsults often demanded in this art, I employ a combination of various means to keep the axis of the part being ground properly and accurately located and in line with the spindle centers, it bein understood that such terms as accurate? as used herein, are to be defined as within the limitations of machine tool manufacture and assembling. To guard against detrimental effects on the grinding operation due to frictional wear in the spindle head and to provide for a. way to adjust for whatever wear does takeplace and secure and maintain alinement of the spindles, my invention embodies in its preferred form the construction illustrated. In accordance therewith the two spindle heads are located so that the hearing axes are alined and parallel with two plane surfaces on the table 12. Each head is provided with two sets of bearings on opposite sides of the gear 21, the bearings having such large. surfaces that there is no great tendency to crush out the oil film between the spindle and bearing surface.

Each set of bearings comprises upper members 32 and lower members 33, the upper members 32 involving semi-cylindrical or half sleeves fixed in the heads 13 and 14 in accurate alinement with each other. Each member 32 is made of very hard material, such as hardened steel, and is subject to a minimum of wear. Therefore the sleeve 32, always remaining true to form and being fixedly mounted in the rigid, massive head, serves as a permanently located guide or gage which contacts with the spindle at a plurality of circumferentially spaced points and is adapted to hold the spindle in correct position when the latter is moved up into close contact with the sleeve.- Since the upper bearings are positioned in accurate alinement with each other, an axis of rotation for the Work .is thereby determined and permanently located.

Due to the weight of the work and the 110 character of the operation being performed, the wear normally takes place in the lower sleeve However, in order to insure wearing only the lower sleeve, I may make it of material relatively softer than the spindle, 116 which preferably is of very hard material and so subject to but little wear. Since the Wear is thus largely localized in the one lower member, it follows that by adjusting or raising this part the spindle may be re- 120 turned to its original position of alinement, as indicated when it is in proper contact with the upper sleeve, serving as a gage therefor.

In order that this raising of the lower 125 sleeve may be accomplishml in a manner permitting the delicate adjustments necessary in this art, I may use the preferred construction illustrated, in which the sleeve 33, shown as provided with a scmi-cylimlri- 130 cal bearing portion 33, has vertical recesses 34: (Fig. 5) in its sides, positioned to receive the squared heads of bolts 35 fixed in the spindle head 13 or 14, whereby the members maybe moved vertically, but are accurately positioned horizontally.

A portion of the lower surface of each bearing member 33 is formed at an angle corresponding to the angle of a slightly tapered wedge 36 upon which it is supported. The wedge 36 is provided with a slotted depending flange 37 the opposite sides of which are engaged by shoulders on an adjusting screw 38 threaded into the head. A

locking screw 39 and plungerAO are provided for holding the screw 38 in ad usted position. The spindle 20 may itself be made of hard material and directly engage the bearing members 32 and 33 or 33, but I consider it preferable to provide the spindle 20 with a hard cylindrical sleeve 41 which is accurately concentric with the spindle, and which may be removed and replaced if it becomes worn or defective. The bearing members 32 and 33 and the sleeves 41 may be provided with outwardly extending flanges 42, as shown at the left-hand bearing in Fig. 4:, these flanges in conjunction with a collar a3 and lock nuts 44 be1ng effective to position the spindle longitudinally in the spindle head.

The heads and their bearings may be initially alined in any feasible manner, as for example, by clamping'the two heads on a straight rod fitting accurately within the four spindle bearings and then machining and scraping the under surfaces of the heads until they lie in'the same plane and fit the table surface. This method insures that when the heads are mounted on the table 12 the upper fixed parts 32 are correctly positioned and it is merely necessary thereafter to adjust the lower bearings to bring the spindles into line. In order that it may be readily determined when the spindles are in alinement, I have provided a ring or cylindrical surface 45 at each end of each spindle, each ring being ground to exactly the same dimensions and having its axis of rotation accurately alined with that of the spindle. Accurately machinedplane surfaces 46 and 47 on the table positioned parallel with the desired work grinding axis of rotation serve as a guide for locating the spindles, so that when it is desired to test for alinement, a dial indicator, located by means of the plane surfaces 46 and 47, is pressed successively against, the rings 45 to determinetheir position, and the wedges 36 are then adjusted until the indicator records the same for each position.

By this construction, I have provided a double head grinding machine in which the work is carried on two rotating spindles positively driven in accurately timed, synthat equivalent elements may be substituted for parts herein disclosed Without departing from the scope of my invention as expressed in the claims appended hereto.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a grinding machine, means for grinding a curved surface, a Work-centering spindle and an alinement member engageable by the spindle and accurately and rigidly positioned to aline the latter with the true work-grinding axis, a movable bearing support for said spindle and fine precision means to adjust said support and locate the spindle against said alinement member in correct position for grinding.

2. In a grinding machine, means for grinding a curved surface, a spindle alinement member having a fixed, hard bearing of a partial surface of revolution, means to hold the axis of said surface permanently alined with the true work axis, a movable wear-receiving bearing member, a hard work-centering spindle rotatably supported thereby and accurately fitting the curved surface of said alinement member, and fine precision means for adjusting the movable member to position the spindle correctly against the fixed bearing.

3. In a machine, two rotatable spindles for centering a piece of work, al-inement 105 guides having surfaces adapted to engage the spindles at a plurality of circumferentially spaced points, said guides. having their spindle engaging surfaces permanently located in such positions that the spindles 110 ing hardened, fixed bearing surfaces of par- 1 20 tial revolution, the axes'of which are permanently alined with each other and the true work-grinding axis of rotation, movably mounted bearing members adapted to re ceive the rotative frictional wear, and means 12 for separately adjusting said movable members to position the spindles against the fixed bearing surfaces in correct alinbment and to take up wear.

5. In a machine, two rotatabe spindles for 180 means for maintaining the axes of said surfaces in permanent alinement with each other and the true work axis, adjustably mounted lower bearing members for the spindles adapted to take the frictional wear and fine precision means for separately adjusting the lower bearing members to position the spindles against the upper bearing surfaces in correct alinement.

6. In a double head grinding machine, means for grinding a surface of rotation, two spindle heads mounted thereon and provided with partial cylindrical upper bearing surfaces of hardened material therein, having their axes of rotation in precise alinement with each other and with the desired axis of rotation of work to be ground, a lower bearing member in'each spindle head, spindles supported in the lower bearings and adapted to center the Work between them, said spindles having cylindrical surfaces with their axes in accurate alinement, the spindle Surfaces being hard and of a large extent so that wear is minimized and necessarily occurs in the lower bearing members, and means for adjusting the lower hearings to position the spindles against the upper bearings in correct alinement.

7. In a double-head grinding machine, means for grinding a curved surface, two spindle'heads, a spindle rotatively mountec in each head and adapted to center the work tobe ground, driving mechanism to rotate said spindles in synchronism, upper bearing members rigidly fixed in each head and having inner surfaces of partial revolution with their axes in alincment and means for supporting the spindles and adjusting them into rotative contact with the upper hearings to aline them with the axes of the bearings.

8. In a double head grinding machine, means for grinding rotating work, two spindle heads, driving means in said heads for centering and rotating the work comprising two rotatable spindles adapted to carrythe work between them, upper hearing members for the spindles having hard hearing surfaces of partial revolution, the axes of which are permanently alined with the true work axis, adjustably mounted lower bearing members supporting said spindles, fine precision mechanism for separately adjusting the lower bearings to move the spindles into correct relationship with the upper bearing surfaces and hence into alinement and means for positively operating said driving means to rotate the spindles in synchronism.

9. in a double head grinding machine, a grinding instrument. a work table. two spindle heads mounted thereon, a spindle rotatively mounted in each head and adapted to support and rotate the work to be ground, driving mechanism including geared connections to rotate said spindles in perfect synchronism, means to take up wear in said geared connections, upper bearing members rigidly fixed in each head and having inner surfaces of identical curvatures of revolution With their axes in a-linement and means for supporting the spindles and 'adjusting them into rotative contact with the upper hearings to aline them with the bearing axes.

10. In a grinding machine, a straight guide thereon parallel with the desired work axis of rotation, an adjustable spindle sup port adapted to have its bearing axis positioned parallel with said guide, a spindlerotatively mounted therein for centering the work, and exteriorly accessible, accurate cylindrical surfaces on said spindle adjacent the ends thereof, the axes of which are in ahnement with the axis of said spindle and may be adjusted into parallelism with said guide to locate the work.

11. In a grinding machine, the combination with a work tab'le having a guide thereon parallel with the desired work-grinding axis of rotation, of a spindle head on said table, bearings therein, aspindle rotatably mounted in the bearings and'adapted to center the work to be ground, an accurate cylindrical surface on each end of the spindle, accessible from outside said head and bearings. the axis of rotation of each of said surfaces being identical with that of the spindle, and means for adjusting the position of said spindle so that the cylindrical surfaces may be brought into parallelism with the plane surface and thereby aline the spindle with the work-grinding axis.

12. In a double head grinding machine for grinding surfaces of rotation to a fine degree of accuracy, a rotative grinding instrument, a work table. spindle heads thereon. upper hearings of hardened material in the heads having downwardly concaved surfacesof like partial cylindrical shape. their axes of rotation being in accurate alinement with the axis of rotation of the work to be ground. a work-siipporting and centering element in each head comprising a hard surfaced spindle rotatirely mounted to fit accurately against said bearing surface, means comprising a lower hearing member to hold each spindle in contact with the upper bearing surface. means for adjusting the position of the spindles, driving gearing operativcly connected to the central portion of cach spindle and mechanism connecting the gearings to rotate them in synchronism.

1 3. in a grinding machine, in combination, a work table, a grinding head on said table. a \rorlesupporting spindie rotatable in said head. means to positively drive said i of this bearing,

spindle and means to preserve the alinement of said spindle, said latter means comprising two part bearings spindle, each bearing comprising a hardened half sleeve fixed in said head and overlying said spindle and a lower bearing member vertically adjustable in said head and underlying said spindle, and means for moving said lower bearing member vertically to compensate for wear.

14. A double head grinding machine having, in combination, a work table, oppositely disposed heads longitudinally adjustable on said table, a work-supporting spindle rotatable in each head, means to positively drive said spindles in unison, and means to preserve the alinement of said spindles, said latter means comprising two part bearings for each end of each spindle, each bearing comprising a hardened half sleeve fixed in said head and overlying said spindle, a lower bearing member underlying said spindle and vertically adjustable in said head, and means for moving said lower bearing member vertically to compensate for wear said means comprising awedge underlying said member and having a down-turned slotted flange at one end, an adjusting screw for said wedge having opposed shoulders engaging both sides of said flange adjacent the slot therein, and means to lock said screw in adjusted position.

15. A double head grinding machine having, in combination, a work table, oppositely disposed heads longitudinally adjustable on said table, a work-supporting spindle rotatable in each head, means to positively drive said spindles in unison, and means to preserve the alinement of said spindles, said latter means comprising two part bearings for each end of each spindle, each bearing comprising a hardened half sleeve fixed in said head and overlying said spindle, a lower bearing member nnderlying said spindle and vertically ad ustable in said head, means for moving said lower bearing member vertically to compensate for wear of the bearing, and means to guide said member in its vertical movement, said latter means comprising vertically extended recesses in the opposite sides of said memfor each end of said her, and lugs detaohably secured to said head and extending into said recesses.

16. A double head grinding machine having, in combination, a move said table longitudinally, oppositely disposed heads longitudinally adjustable on said table, means to adjust said heads and to secure said heads in adjusted position, a work-supporting spindle in each head, a driving shaft mounted in bearings table, an intermediate shaft mounted in each head, a. positive gear drive between each intermediate shaft and said driving shaft including a sliding connection permitting longitudinal adjustment of said heads, a positive gear connection from each intermediate shaft toits associated spindle and means for alining the spindles in their bearings as the parts become worn. a

17. A double head grinding machine having, in combination, a work table, 'means to move said table longitudinally, oppositely disposed heads longitudinally adjustable on said table, means to adjust said heads and to secure said heads in adjusted position, a work-supporting spindle in each head, a driving shaft mounted in bearings in said table, a positive geared drivin connection from said shaft to each work spindle, whereby said spindles are positively and synchronously rotated, and means for taking up wear in said geared connection.

18. In a grinding machine, a head, a work-supporting spindle, separated bearings in said head for said spindle, and a driving gear on said spindle between said bearings, said gear having means to compensate for wear of the teeth, and said bearings having means to restore said spindle to its original alinemen said latter means comprising a; hardened half sleeve forming the upper part of said bearing, a lower bearing member and means to adjust said lower member verti cally.

Signed at Worcester, Massachusetts, this 5th day of July, 1917.

CHARLES H. NORTON.

Witnesses LEWIS F. BUTTERFIELD, CLAYTON L. J ENKS.

work table, means to in said 0 

